The invention relates to apparatus for cooking raw product, such as shellfish and the like, and, more particularly, to a feed mechanism for accurately controlling the amount of product deposited on a conveyor belt for transport out of a feed tank into a cooking chamber.
Cooking shrimp and other shellfish in a continuous cooking process is well known. In cooking shrimp, for instance, raw shrimp in a feed tank are deposited on an endless conveyor belt that lifts the shrimp out of the tank into and through a cooking compartment in which the shrimp are cooked. At the exit end of the cooking compartment, the shrimp drop from the conveyor belt for further processing. For example, they can be dropped into a peeling apparatus that removes the shells through the action of counter-rotating rollers. Such a cooking/peeling apparatus is described in U.S. Pat. No. Re. 34,646, "APPARATUS FOR CONTROLLING PRE-COOKING AND MACHINE PEELING SHRIMP," issued Jun. 28, 1994. The patent also describes a feed mechanism for a fluid-filled tank that includes an oscillating feed paddle secured to a rocking shaft. A rocker arm extends from the rocking shaft to a pivotal connection with an adjustable-length pitman drive all. The other end of the pitman drive arm is pivotally attached to a rotary drive train. The rotary motion of the drive train imparts a swinging motion to the paddle through the arms. The throw range of each swing of the paddle is controlled by adjusting the length of the pitman arm. The throw determines the quantity of shrimp deposited by wave action on the conveyor belt.
In many applications, it is desirable for health reasons to separate raw product from cooked product. The Model CTSH Split Hood Pure Steam Cooker manufactured by Laitram Machinery, Inc. of Harahan, La., USA, for example, is designed to be installed through a physical divider or wall to separate product into low and high risk zones. The cooker is positioned with the raw product feed tank and the entrance end of the cooker in the low risk zone on one side of the divider and the exit end of the cooker through which the cooked shrimp pass in the high risk zone on the opposite side of the divider. In this way, contamination of cooked product in the high risk zone by migration of bacteria and other contaminants found in the raw product in the low risk zone is all but eliminated.
Nevertheless, human traffic between zones increases the chances of cross-contamination. Such traffic is often necessary when adjusting the product flow rate. Because the machine operator is usually stationed in the high risk zone and the flow rate is typically adjusted by varying the length of the pitman arm in the low risk zone, travel between the two zones is inevitable. A remote paddle adjuster having an adjustment handle in the high risk zone that hydraulically adjusts the length of the pitman arm to control the paddle and product flow is an optional accessory of the Laitram Model CTSH cooker. Such a remote adjustment tool does a good job of preventing cross-contamination, but is rather expensive. Like all hydraulic systems, it is also subject to air bubbles and other contaminants in the hydraulic lines, fluid leaks, and variations in settings with temperature and cook time. These shortcomings make remote, accurate, repeatable settings of product flow difficult.
In the feed tank and cooker systems described thus far, it is preferable to maintain the high risk zone at a higher atmospheric pressure than the low risk zone. This further keeps contaminants from migrating into the high risk zone. One shortcoming of this pressure differential, however, is that it causes a draft through the cooker from exit end to entrance end that tends to blow steam out through the entrance to the cooker in the vicinity of the feed tank. This escape of steam is energy inefficient.
Thus, there is a need for an inexpensive and accurate feed mechanism that can be remotely adjusted to control product flow from a feed tank onto a conveyor system for further processing. There is also a need for a feed tank that can be scaled to a cooker, for instance, to prevent the escape of useful cooking gases via the feed tank.